I added bones, how do I add their vertex groups
If you have done no weight painting for either the body or clothes and have the standard pose available simply parent again the armature.


It seems in newer versions of Blender it will replace the first armature the old armature is reused or deleted.  Make sure you do not get two armature modifiers.  You can also delete the armature modifier, and then parent again.

If you have done significant weight painting and want to keep those weights you can lock the current weights in the vertex groups panel.  Next parent again. I suggest you try this with an archived file if only to prevent some superstitious catastrophe.